Admonishing people gathering for the funeral prayer
7-5-2009 | IslamWeb
Question:
is it permissible to give exortation to people who assemble for janaza salaah.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
Admonishing people and reminding them of Allaah is permissible in principle, as Allaah Says (what means): {Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. Indeed, your Lord is most knowing of who has strayed from His way, and He is most knowing of who is [rightly] guided.}[Quran 16:125]
Therefore, if a person preaches to people before or after the funeral prayer, or before or after the burial of the dead, and he does not take this as a habit, then we hope that it is permissible. However, taking this as a habit would make people believe that it is desirable and legislated to preach at this precise circumstance, and this would render it an innovation. It is for this reason that when Shaykh ‘Uthaymeen 
was asked about preaching at a grave he said: “Preaching at a grave is permissible according to the Sunnah, but not like a person standing and preaching the people because this was not reported from the Prophet especially if this is taken as a habit, every time that person would go with a funeral procession, he would stand to preach the people. Rather preaching at a grave should be in the same manner as the Prophet did, he preached the people while standing at the grave saying: “There is no one of you except that his position in Paradise and Hellfire is written.” Moreover, once he was in Al-Baqee’ graveyard in a funeral and the grave was not yet dug, and he sat down and the companions sat down around him, and he started tracing the ground with a stick which was with him, and then he mentioned the condition of a man when he breathes his last and when he is buried. So he said statements which were in reality a sermon. Such a preaching is permissible, but for a man to stand giving a speech to preach to people, then this is not reported from the Prophet .”
Allaah Knows best.